[PATCH v3 11/12] signal: Deliver all of the siginfo perf data in _perf

From: Eric W. Beiderman
Date: Wed May 05 2021 - 10:12:23 EST

Next message: Eric W. Beiderman: "[PATCH v3 12/12] signalfd: Remove SIL_FAULT_PERF_EVENT fields from signalfd_siginfo"
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From: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>

Don't abuse si_errno and deliver all of the perf data in _perf member
of siginfo_t.

The data field in the perf data structures in a u64 to allow a pointer
to be encoded without needed to implement a 32bit and 64bit version of
the same structure. There already exists a 32bit and 64bit versions
siginfo_t, and the 32bit version can not include a 64bit member as it
only has 32bit alignment. So unsigned long is used in siginfo_t
instead of a u64 as unsigned long can encode a pointer on all
architectures linux supports.

v1: https://lkml.kernel.org/r/m11rarqqx2.fsf_-_@xxxxxxxxxxxxxxxxx
v2: https://lkml.kernel.org/r/20210503203814.25487-10-ebiederm@xxxxxxxxxxxx
Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
---
arch/arm/kernel/signal.c | 3 ++-
arch/arm64/kernel/signal.c | 3 ++-
arch/arm64/kernel/signal32.c | 3 ++-
arch/sparc/kernel/signal32.c | 3 ++-
arch/sparc/kernel/signal_64.c | 3 ++-
arch/x86/kernel/signal_compat.c | 6 ++++--
fs/signalfd.c | 3 ++-
include/linux/compat.h | 5 ++++-
include/uapi/asm-generic/siginfo.h | 8 +++++--
include/uapi/linux/signalfd.h | 4 ++--
kernel/signal.c | 21 ++++++++++++-------
.../selftests/perf_events/sigtrap_threads.c | 12 +++++------
12 files changed, 47 insertions(+), 27 deletions(-)

diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index 643bcb0f091b..f3800c0f428b 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -757,7 +757,8 @@ static_assert(offsetof(siginfo_t, si_addr_lsb) == 0x10);
static_assert(offsetof(siginfo_t, si_lower) == 0x14);
static_assert(offsetof(siginfo_t, si_upper) == 0x18);
static_assert(offsetof(siginfo_t, si_pkey) == 0x14);
-static_assert(offsetof(siginfo_t, si_perf) == 0x10);
+static_assert(offsetof(siginfo_t, si_perf_data) == 0x10);
+static_assert(offsetof(siginfo_t, si_perf_type) == 0x14);
static_assert(offsetof(siginfo_t, si_band) == 0x0c);
static_assert(offsetof(siginfo_t, si_fd) == 0x10);
static_assert(offsetof(siginfo_t, si_call_addr) == 0x0c);
diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index ad4bd27fc044..b3978b468bd4 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -1005,7 +1005,8 @@ static_assert(offsetof(siginfo_t, si_addr_lsb) == 0x18);
static_assert(offsetof(siginfo_t, si_lower) == 0x20);
static_assert(offsetof(siginfo_t, si_upper) == 0x28);
static_assert(offsetof(siginfo_t, si_pkey) == 0x20);
-static_assert(offsetof(siginfo_t, si_perf) == 0x18);
+static_assert(offsetof(siginfo_t, si_perf_data) == 0x18);
+static_assert(offsetof(siginfo_t, si_perf_type) == 0x20);
static_assert(offsetof(siginfo_t, si_band) == 0x10);
static_assert(offsetof(siginfo_t, si_fd) == 0x18);
static_assert(offsetof(siginfo_t, si_call_addr) == 0x10);
diff --git a/arch/arm64/kernel/signal32.c b/arch/arm64/kernel/signal32.c
index ee6c7484e130..d3be01c46bec 100644
--- a/arch/arm64/kernel/signal32.c
+++ b/arch/arm64/kernel/signal32.c
@@ -489,7 +489,8 @@ static_assert(offsetof(compat_siginfo_t, si_addr_lsb) == 0x10);
static_assert(offsetof(compat_siginfo_t, si_lower) == 0x14);
static_assert(offsetof(compat_siginfo_t, si_upper) == 0x18);
static_assert(offsetof(compat_siginfo_t, si_pkey) == 0x14);
-static_assert(offsetof(compat_siginfo_t, si_perf) == 0x10);
+static_assert(offsetof(compat_siginfo_t, si_perf_data) == 0x10);
+static_assert(offsetof(compat_siginfo_t, si_perf_type) == 0x14);
static_assert(offsetof(compat_siginfo_t, si_band) == 0x0c);
static_assert(offsetof(compat_siginfo_t, si_fd) == 0x10);
static_assert(offsetof(compat_siginfo_t, si_call_addr) == 0x0c);
diff --git a/arch/sparc/kernel/signal32.c b/arch/sparc/kernel/signal32.c
index 5573722e34ad..4276b9e003ca 100644
--- a/arch/sparc/kernel/signal32.c
+++ b/arch/sparc/kernel/signal32.c
@@ -778,6 +778,7 @@ static_assert(offsetof(compat_siginfo_t, si_addr_lsb) == 0x10);
static_assert(offsetof(compat_siginfo_t, si_lower) == 0x14);
static_assert(offsetof(compat_siginfo_t, si_upper) == 0x18);
static_assert(offsetof(compat_siginfo_t, si_pkey) == 0x14);
-static_assert(offsetof(compat_siginfo_t, si_perf) == 0x10);
+static_assert(offsetof(compat_siginfo_t, si_perf_data) == 0x10);
+static_assert(offsetof(compat_siginfo_t, si_perf_type) == 0x14);
static_assert(offsetof(compat_siginfo_t, si_band) == 0x0c);
static_assert(offsetof(compat_siginfo_t, si_fd) == 0x10);
diff --git a/arch/sparc/kernel/signal_64.c b/arch/sparc/kernel/signal_64.c
index a69a78984c36..cea23cf95600 100644
--- a/arch/sparc/kernel/signal_64.c
+++ b/arch/sparc/kernel/signal_64.c
@@ -588,6 +588,7 @@ static_assert(offsetof(siginfo_t, si_addr_lsb) == 0x18);
static_assert(offsetof(siginfo_t, si_lower) == 0x20);
static_assert(offsetof(siginfo_t, si_upper) == 0x28);
static_assert(offsetof(siginfo_t, si_pkey) == 0x20);
-static_assert(offsetof(siginfo_t, si_perf) == 0x18);
+static_assert(offsetof(siginfo_t, si_perf_data) == 0x18);
+static_assert(offsetof(siginfo_t, si_perf_type) == 0x20);
static_assert(offsetof(siginfo_t, si_band) == 0x10);
static_assert(offsetof(siginfo_t, si_fd) == 0x14);
diff --git a/arch/x86/kernel/signal_compat.c b/arch/x86/kernel/signal_compat.c
index c9601f092a1e..b52407c56000 100644
--- a/arch/x86/kernel/signal_compat.c
+++ b/arch/x86/kernel/signal_compat.c
@@ -147,8 +147,10 @@ static inline void signal_compat_build_tests(void)
BUILD_BUG_ON(offsetof(siginfo_t, si_pkey) != 0x20);
BUILD_BUG_ON(offsetof(compat_siginfo_t, si_pkey) != 0x14);

- BUILD_BUG_ON(offsetof(siginfo_t, si_perf) != 0x18);
- BUILD_BUG_ON(offsetof(compat_siginfo_t, si_perf) != 0x10);
+ BUILD_BUG_ON(offsetof(siginfo_t, si_perf_data) != 0x18);
+ BUILD_BUG_ON(offsetof(siginfo_t, si_perf_type) != 0x20);
+ BUILD_BUG_ON(offsetof(compat_siginfo_t, si_perf_data) != 0x10);
+ BUILD_BUG_ON(offsetof(compat_siginfo_t, si_perf_type) != 0x14);

CHECK_CSI_OFFSET(_sigpoll);
CHECK_CSI_SIZE (_sigpoll, 2*sizeof(int));
diff --git a/fs/signalfd.c b/fs/signalfd.c
index 83130244f653..335ad39f3900 100644
--- a/fs/signalfd.c
+++ b/fs/signalfd.c
@@ -134,7 +134,8 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
break;
case SIL_FAULT_PERF_EVENT:
new.ssi_addr = (long) kinfo->si_addr;
- new.ssi_perf = kinfo->si_perf;
+ new.ssi_perf_type = kinfo->si_perf_type;
+ new.ssi_perf_data = kinfo->si_perf_data;
break;
case SIL_CHLD:
new.ssi_pid = kinfo->si_pid;
diff --git a/include/linux/compat.h b/include/linux/compat.h
index 6af7bef15e94..a27fffaae121 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -236,7 +236,10 @@ typedef struct compat_siginfo {
u32 _pkey;
} _addr_pkey;
/* used when si_code=TRAP_PERF */
- compat_ulong_t _perf;
+ struct {
+ compat_ulong_t _data;
+ u32 _type;
+ } _perf;
};
} _sigfault;

diff --git a/include/uapi/asm-generic/siginfo.h b/include/uapi/asm-generic/siginfo.h
index 3503282021aa..3ba180f550d7 100644
--- a/include/uapi/asm-generic/siginfo.h
+++ b/include/uapi/asm-generic/siginfo.h
@@ -96,7 +96,10 @@ union __sifields {
__u32 _pkey;
} _addr_pkey;
/* used when si_code=TRAP_PERF */
- unsigned long _perf;
+ struct {
+ unsigned long _data;
+ __u32 _type;
+ } _perf;
};
} _sigfault;

@@ -159,7 +162,8 @@ typedef struct siginfo {
#define si_lower _sifields._sigfault._addr_bnd._lower
#define si_upper _sifields._sigfault._addr_bnd._upper
#define si_pkey _sifields._sigfault._addr_pkey._pkey
-#define si_perf _sifields._sigfault._perf
+#define si_perf_data _sifields._sigfault._perf._data
+#define si_perf_type _sifields._sigfault._perf._type
#define si_band _sifields._sigpoll._band
#define si_fd _sifields._sigpoll._fd
#define si_call_addr _sifields._sigsys._call_addr
diff --git a/include/uapi/linux/signalfd.h b/include/uapi/linux/signalfd.h
index 7e333042c7e3..e78dddf433fc 100644
--- a/include/uapi/linux/signalfd.h
+++ b/include/uapi/linux/signalfd.h
@@ -39,8 +39,8 @@ struct signalfd_siginfo {
__s32 ssi_syscall;
__u64 ssi_call_addr;
__u32 ssi_arch;
- __u32 __pad3;
- __u64 ssi_perf;
+ __u32 ssi_perf_type;
+ __u64 ssi_perf_data;

/*
* Pad strcture to 128 bytes. Remember to update the
diff --git a/kernel/signal.c b/kernel/signal.c
index 49560ceac048..7fec9d1c5b11 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1758,11 +1758,13 @@ int force_sig_perf(void __user *addr, u32 type, u64 sig_data)
struct kernel_siginfo info;

clear_siginfo(&info);
- info.si_signo = SIGTRAP;
- info.si_errno = type;
- info.si_code = TRAP_PERF;
- info.si_addr = addr;
- info.si_perf = sig_data;
+ info.si_signo = SIGTRAP;
+ info.si_errno = 0;
+ info.si_code = TRAP_PERF;
+ info.si_addr = addr;
+ info.si_perf_data = sig_data;
+ info.si_perf_type = type;
+
return force_sig_info(&info);
}

@@ -3380,7 +3382,8 @@ void copy_siginfo_to_external32(struct compat_siginfo *to,
break;
case SIL_FAULT_PERF_EVENT:
to->si_addr = ptr_to_compat(from->si_addr);
- to->si_perf = from->si_perf;
+ to->si_perf_data = from->si_perf_data;
+ to->si_perf_type = from->si_perf_type;
break;
case SIL_CHLD:
to->si_pid = from->si_pid;
@@ -3456,7 +3459,8 @@ static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
break;
case SIL_FAULT_PERF_EVENT:
to->si_addr = compat_ptr(from->si_addr);
- to->si_perf = from->si_perf;
+ to->si_perf_data = from->si_perf_data;
+ to->si_perf_type = from->si_perf_type;
break;
case SIL_CHLD:
to->si_pid = from->si_pid;
@@ -4639,7 +4643,8 @@ static inline void siginfo_buildtime_checks(void)
CHECK_OFFSET(si_lower);
CHECK_OFFSET(si_upper);
CHECK_OFFSET(si_pkey);
- CHECK_OFFSET(si_perf);
+ CHECK_OFFSET(si_perf_data);
+ CHECK_OFFSET(si_perf_type);

/* sigpoll */
CHECK_OFFSET(si_band);
diff --git a/tools/testing/selftests/perf_events/sigtrap_threads.c b/tools/testing/selftests/perf_events/sigtrap_threads.c
index 78ddf5e11625..fde123066a8c 100644
--- a/tools/testing/selftests/perf_events/sigtrap_threads.c
+++ b/tools/testing/selftests/perf_events/sigtrap_threads.c
@@ -164,8 +164,8 @@ TEST_F(sigtrap_threads, enable_event)
EXPECT_EQ(ctx.signal_count, NUM_THREADS);
EXPECT_EQ(ctx.tids_want_signal, 0);
EXPECT_EQ(ctx.first_siginfo.si_addr, &ctx.iterate_on);
- EXPECT_EQ(ctx.first_siginfo.si_errno, PERF_TYPE_BREAKPOINT);
- EXPECT_EQ(ctx.first_siginfo.si_perf, TEST_SIG_DATA(&ctx.iterate_on));
+ EXPECT_EQ(ctx.first_siginfo.si_perf_type, PERF_TYPE_BREAKPOINT);
+ EXPECT_EQ(ctx.first_siginfo.si_perf_data, TEST_SIG_DATA(&ctx.iterate_on));

/* Check enabled for parent. */
ctx.iterate_on = 0;
@@ -183,8 +183,8 @@ TEST_F(sigtrap_threads, modify_and_enable_event)
EXPECT_EQ(ctx.signal_count, NUM_THREADS);
EXPECT_EQ(ctx.tids_want_signal, 0);
EXPECT_EQ(ctx.first_siginfo.si_addr, &ctx.iterate_on);
- EXPECT_EQ(ctx.first_siginfo.si_errno, PERF_TYPE_BREAKPOINT);
- EXPECT_EQ(ctx.first_siginfo.si_perf, TEST_SIG_DATA(&ctx.iterate_on));
+ EXPECT_EQ(ctx.first_siginfo.si_perf_type, PERF_TYPE_BREAKPOINT);
+ EXPECT_EQ(ctx.first_siginfo.si_perf_data, TEST_SIG_DATA(&ctx.iterate_on));

/* Check enabled for parent. */
ctx.iterate_on = 0;
@@ -203,8 +203,8 @@ TEST_F(sigtrap_threads, signal_stress)
EXPECT_EQ(ctx.signal_count, NUM_THREADS * ctx.iterate_on);
EXPECT_EQ(ctx.tids_want_signal, 0);
EXPECT_EQ(ctx.first_siginfo.si_addr, &ctx.iterate_on);
- EXPECT_EQ(ctx.first_siginfo.si_errno, PERF_TYPE_BREAKPOINT);
- EXPECT_EQ(ctx.first_siginfo.si_perf, TEST_SIG_DATA(&ctx.iterate_on));
+ EXPECT_EQ(ctx.first_siginfo.si_perf_type, PERF_TYPE_BREAKPOINT);
+ EXPECT_EQ(ctx.first_siginfo.si_perf_data, TEST_SIG_DATA(&ctx.iterate_on));
}

TEST_HARNESS_MAIN
--
2.30.1

Next message: Eric W. Beiderman: "[PATCH v3 12/12] signalfd: Remove SIL_FAULT_PERF_EVENT fields from signalfd_siginfo"
Previous message: Min Li: "RE: [PATCH mfd v1] mfd: Add Renesas Synchronization Management Unit (SMU) support"
In reply to: Peter Zijlstra: "Re: [PATCH v3 10/12] signal: Factor force_sig_perf out of perf_sigtrap"
Next in thread: Marco Elver: "Re: [PATCH v3 11/12] signal: Deliver all of the siginfo perf data in _perf"
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